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Week 2 · Season 1 · Spark

A letter across the planet

You can explain how a message crosses the internet, what happens in a web request, read JSON from an API, keep keys secret, and make your first call to a free AI model.

Open week 2 in the app

This week

  • Packets, addresses, routers and DNS
  • Clients, servers, HTTP and status codes
  • APIs, JSON, keys and secrets
  • What a language model is, in plain words
  • Tokens, limits, cost and free tiers

How you learn

Trace one request by hand: from your keyboard, through DNS and the network, to a server and back. Then price one AI call before you make it.

What you build

FRIDAY talks: connect it to a free model so it chats in your terminal and remembers the conversation while it runs.

Stretch: Show how many tokens each message used and what it would cost on a paid plan.

What you ship

  • A chat command that remembers earlier turns
  • Your API key read from the environment, never in the code

Lessons

  1. A letter across the planet

    After this deck you can explain how a message crosses the internet: chopped into packets with an address on each, passed hop by hop by routers, with DNS turning names into number addresses.

    10 minFull access

  2. Ask and answer

    After this deck you can say what a client and a server are, read an HTTP request and response, and tell from a status code whether the problem is your ask (4xx) or the server (5xx).

    10 minFull access

  3. Menus for machines

    After this deck you can say what an API is, read a JSON reply and pick out fields with Python, and keep an API key out of your code in an environment variable.

    12 minFull access

  4. Autocomplete that read the library

    After this deck you can explain a language model in plain words (an autocomplete that learned patterns from a huge library of text), and build the request for your first call to a free model.

    12 minFull access

  5. Every word has a price

    After this deck you can explain tokens, estimate what a call would cost, plan a chat inside a free tier's limits, and say why the same question can get different answers.

    12 minFull access

  6. Go deeper: how a request really travels

    After this deck you can explain when the internet uses careful TCP or quick UDP, read a traceroute, and say what HTTPS and a certificate protect you from.

    12 minFull accessGo deeper · optional

Labs

Python in the browser, next to the lessons.

Weekend build

Skills you prove

Networks & HTTP
Explain how a request crosses the internet and read an HTTP request and response
Token math
Price any call in input, output and cached tokens, and report cost per task

Hand-picked official docs, papers and talks.